Two-junction photovoltaic devices

Abstract

The present disclosure relates to a photovoltaic (PV) device that includes a first junction constructed with a first alloy and having a bandgap between about 1.0 eV and about 1.5 eV, and a second junction constructed with a second alloy and having a bandgap between about 0.9 eV and about 1.3 eV, where the first alloy includes III-V elements, the second alloy includes III-V elements, and the PV device is configured to operate in a thermophotovoltaic system having an operating temperature between about 1500° C. and about 3000° C.

What is claimed is: 
     
       1. A thermophotovoltaic (TPV) device comprising, in order:
 a first junction having a first composition comprising Al x Ga 1-x As; 
 a tunnel junction having a second composition comprising at least one of GaAs or AlGaAs; 
 a buffer layer having a third composition comprising at least one of Ga y In 1-y P or Al a Ga b In 1-a-b As; and 
 a second junction having a fourth composition comprising Ga c In 1-c As, wherein: 
 the first junction has a bandgap between 1.3 eV and 1.5 eV, 
 the second junction has a bandgap between 1.1 eV and 1.3 eV, 
 0≤x≤0.45, 
 0.20<y<0.51, 
 0.15≤a≤0.70, 
 0.25≤b≤0.60, 
 0.70≤c≤0.95, and 
 the TPV device is configured to absorb light from a blackbody operating at a temperature, T w , between 1500° C. and 3000° C. 
 
     
     
       2. The TPV device of  claim 1 , wherein the first composition is GaAs. 
     
     
       3. The TPV device of  claim 1 , wherein the third composition is Ga y In 1-y P and 0.32≤y≤0.51. 
     
     
       4. The TPV device of  claim 1 , wherein the buffer layer is a compositionally graded buffer (CGF) layer. 
     
     
       5. The TPV device of  claim 4 , wherein:
 the CGF layer comprises between 2 and 15 graded layers, 
 each graded layer comprises the third composition, and 
 the graded layer adjacent to the second junction is lattice-matched to the second junction. 
 
     
     
       6. The TPV device of  claim 1 , wherein the fourth composition is substantially equal to Ga 0.85 In 0.15 As. 
     
     
       7. The TPV device of  claim 1 , wherein T w  is between 1900° C. and 2400° C. 
     
     
       8. The TPV device of  claim 1 , further comprising:
 a substrate comprising at least one of GaAs or Ge, wherein: 
 the first junction is positioned between the substrate and the tunnel junction.